Rangers' Nikica Jelavic is now a target for Everton following interest from a number of English clubs. Photograph: David Moir/Reuters

Between the Old Firm, the upcoming transfer window holds more potential intrigue – and fear – for supporters of Rangers. The Scottish Premier League leaders have been wounded by the loss of Steven Naismith to serious injury. Naismith, Allan McGregor, Steven Davis and Nikica Jelavic are widely and rightly regarded as the quartet who form such an firm backbone to the Rangers team.

It would be unfair not to recognise the defensive contributions of Carlos Bocanegra and Dorin Goian to Ally McCoist's side already this season. Still, a further injury or the exit of another of Rangers' key players would seem likely to inflict a fatal blow on their championship aspirations. The club has already made it clear it will not be spending lavish sums in an attempt to retain the SPL title. Being blunt about it, they are not in any position to do so anyway.

Against this backdrop, the situation with Jelavic is the most interesting. Everton have now become the latest club to be linked with a move for the Croatia international striker; Leicester City, West Brom, Sunderland and Liverpool have already been quoted as admirers.

By McCoist's own private admission, if a significant bid arrives for Jelavic from south of the border, Rangers are hardly likely to rebuff it. When Walter Smith sanctioned the £4m purchase of Jelavic from Rapid Vienna, a clear part of his strategy would have been the potential sale of the 26-year-old for a higher sum at some point in the future. The current problem for Rangers is that they lack the strength in depth which could handle the loss of their principal goal threat.

John Brown, the head of Rangers' scouting operations, has been watching a series of Championship matches recently. Brown's aim is clear: to find a centre-forward. The great unknown, even to McCoist, is whether that is to assist or replace Jelavic. The Rangers manager admitted earlier this season that he wanted attacking alternatives, before Jelavic started to become linked with new employers with such regularity. Worryingly for McCoist – Sone Aluko possibly aside – the Rangers recruitment of attacking players recently has failed to impress.

Jelavic's appeal to English sides is clear. He has excellent physicality and can provide a wide range of goals. As is the sign of a fine striker, he can score even when not playing well and secure points for his team when others are struggling. His league record in Scotland shows 28 goals in just 36 starts. A mid-range English Premier League team would seem a reasonable level of aspiration for now.

One can only presume that, when departing Austria for Glasgow in the summer of 2010, Scottish football was not the summit of Jelavic's ambitions. That much is as natural as, no matter the situation with the club's ownership, an SPL team looking to make profit on a player. Rangers, even in their free-spending days, would not have been averse to letting a player of Jelavic's ilk leave for a decent profit.

Although it pains certain elements of their supporter base to hear it, Celtic and Rangers are now little more than feeder clubs for those south of the border or richer outfits elsewhere. Their best players will be coaxed away without much delay. Such a scenario should not automatically be regarded as damaging, as long as reasonable transfer fees are picked up and strong enough scouting operations are in place that there is at least a consistent flow of talent arriving year on year.

Rangers have assets in McGregor, Davis, Naismith – injuries notwithstanding – and Jelavic. Celtic, too, could easily sell Beram Kayal, Gary Hooper and – although also currently injured – Emilio Izaguirre. Of that batch, Jelavic's loss would almost certainly be the most keenly felt, were he to be sold in January.

Craig Whyte's plans for Rangers, the detail of which remains largely unclear, cannot have been helped by a further delay to the tax tribunal which is set to shape their future. Until the result of this ongoing, high-profile affair is determined, more questions than answers hover over Ibrox.

In the meantime, with no European revenue to supplement Rangers, the owner must either subsidise them from his own pocket or secure some form of lending. A third option, quite clearly, is to sell a player or players to keep the books balanced. When Rangers rebuffed at least one bid for Jelavic in August, their situation did not quite seem as desperate as many had earlier believed.

In the coming months, the Rangers support would prefer to focus on matters on the field. Amid ever-increasing speculation, despair or delight are the only possible emotions they can feel in relation to Jelavic by 1 February.